How to compare colors in swift

Previous answers are wrong cause

UIColor.black.isEqual(UIColor(red: 0, green: 0, blue: 0, alpha: 1))

returns false

add this code to your project (Swift 4)

extension UIColor {
  static func == (l: UIColor, r: UIColor) -> Bool {
    var r1: CGFloat = 0
    var g1: CGFloat = 0
    var b1: CGFloat = 0
    var a1: CGFloat = 0
    l.getRed(&r1, green: &g1, blue: &b1, alpha: &a1)
    var r2: CGFloat = 0
    var g2: CGFloat = 0
    var b2: CGFloat = 0
    var a2: CGFloat = 0
    r.getRed(&r2, green: &g2, blue: &b2, alpha: &a2)
    return r1 == r2 && g1 == g2 && b1 == b2 && a1 == a2
  }
}
func == (l: UIColor?, r: UIColor?) -> Bool {
  let l = l ?? .clear
  let r = r ?? .clear
  return l == r
}

so now

UIColor.black == UIColor(red: 0, green: 0, blue: 0, alpha: 1)

returns true

and for you:

if sender.backgroundColor == .red {
  sender.backgroundColor = .white
} else {
  sender.backgroundColor = .red
}

now your code looks pretty :)

You don't compare colors using the == operator. You do it like this and you need the ! to unwrap the optional color:

if sender.backgroundColor!.isEqual(UIColor.redColor()) {
            
}

Also, remove the extraneous = in your assignment statement. It should be:

sender.backgroundColor = UIColor.whiteColor()